Pemerton's example fighter needs to pump STR religiously, pick up Weapon Expertise pretty soon, and probably work on ways to exploit his weapon of choice (Heavy Blade Expertise, Hafted Defense, maybe one of the style masteries from MP2, etc.). In paragon he can access the polearm feats, acquire threatening reach, etc. too if he wants.
Pemerton's Fighter I think is PHB 1/2 only. But here are the likely ways that it didn't matter:
Pemerton could simply not throw unusually high AC opponents into the mix. Less Soldiers, more Brutes.
Pemerton could hand out more magic items. Having a +2 Halberd at say 3rd level wouldn't be too unusual, but would help with hitting.
The party could have a leader who handed out bonuses to hit and as a whole, the party would be focused on gaining flanks for Combat Advantage.
Sure. He could also emphasize things in his build like damage output and mark punishment, which were better supported in early 4e than increased to-hit.
Every player in my game has added to the PC's main stat at every ability gain. Including the dwarf fighter.
The fighter had the first magic weapon - a +1 weapon taken from a defeated higher-level NPC - but after the initial moments of item acquisition the increase in pluses has tended to be along the lines of the AV GM-mandated power-ups, which have been pretty constant across all the PCs as best I can recall (I probably have a record of it somewhere, but haven't dug it out for this post).
With Passing Attack, you need to hit first to get your second attack - I can't remember now exactly what strategies were used to help with this, but I would guess that combat advantage would be the main one (no leader in the party until at 6th level the player of the archer-ranger rebuilt the character as a hybrid ranger-cleric). From 3rd level the main strategy for hitting has been multiple attacks (the CB1 attack which adds STR to hit; then CaGI at 7th; etc).
From around 7th level, the PC has been the party's primary controller - by using CaGI, Footwork Lure, etc for positioning and then marking plus from somewhere around paragon the feat (with "pin" in the name) that immobilises a marked creature on a basic attack hit (and WIS bonus to OAs mean the character has never had much trouble landing basic attack hits).
As came up in some other recent thread (and provoked a response from [MENTION=996]Tony Vargas[/MENTION]) the PC is the most complicated at the table to play during combat, in terms of interactions between forced movement, feats that knock prone (Polearm Momentum, plus some OA booster), grant CA (Deadly Draw), immobilise (the "pin" one), knowing which attack sequence to use to activate which feats, knowing which weapon to use (he alternates between hablerd for reach and mordenkrad for damage), knowing when to heal, etc.
I don't like the "glom onto a single target till it's dead, then move to the next" gameplay, so as a DM I discourage it by running monsters more tactically than the players are running their character, to push them to engage with the entire enemy force.
I agree with this. Focus fire is boring. Superhero comics generally don't emphasise it. Action movies generally don't emphasise it.
As a GM - similar to what you describe - I use the NPCs/monsters in a way that tries to force engagement of the whole situation. The fact that 3 of 5 PCs in my main 4e game have multi-target attacks (close bursts for the fighter, area bursts for the sorcerer and invoker) tends to make this easier, and reduce the sense of focus fire.
Another way this works is to set things up so one (or both) of the defenders is keeping some particularly dangerous enemy off the rest of the group. Eg I remember when the PCs assaulted Torog's Soul Abattoir, the fighter solo-ed a Death Titan; and in the current situation in the game, the paladin is keepin a Hundred-handed One off the rest of the party. (Which is a signiicant debuff for the NPC, which gets one attack per nearby enemy.)